Non-iPad tablets are starting to proliferate and some of them are getting positive reviews. For example, ZDNet's Matthew Miller has given the new HTC Flyer 7" Android tablet a very positive review. It features the HTC Sense UI and some other proprietary software tweaks. However its main differentiator is a stylus/pen (sold separately) that works with the tablet.
This is unique in the market and could be a nice feature for artists and those who want to draw on the device -- or students making notes while reading or in classs.
Android Central gives the new Samsung Android 10.1" tablet a very positive review as well. However I find the 10.1 size, which favors the portrait angle, awkward. With a smaller form factor I would be more enthusiastic. Beyond this, however the software experience simply doesn't stand up to the iPad. My biggest pet peeve is that all websites are read as mobile, which doesn't take advantage of the larger form factor. In addition almost none of the Android apps have been optimized for tablets at this point.
If I'd never used an iPad the Samsung device would be impressive in many respects. However one must get used to the navigation, among other things, on the Honeycomb device. I've said this many times in the past but I think the winning Android tablets will be 7" especially given no Apple entry in that smaller category.
The RIM Playbook is 7" and appeared to be selling well according to some preliminary reports. However a new report suggests that the device is actually not selling very well and experiencing a high return rate. We'll have to wait until the next RIM earnings report to learn the truth. The Playbook is supposed to be able to run Android apps, which was a shrewd and critical decision by RIM. Otherwise it would be DOA. Even so, it may not survive.
The first Android "flagship" tablet, the 10" Motorola Xoom, is effectively a flop. And HP/Palm is making lots of boasts and claims about its forthcoming TouchPad (which will be priced at $499 and $599). However the 9.7" device also likely to fail if it tries to go head to head with the iPad.
Putting aside eReaders, by this time next year there will probably be three categories of tablets: 10", 7" and a smaller category that will include everything else: iPod Touch, Galaxy Player, Dell Streak, etc. Almost all non-iPad tablets (unless they're very inexpensive) will fail at the 10" level.
However there will be several viable mostly Android competitors at the 7" level, chiefly because Apple isn't present. Apple has said it's not ceding any segment but it's unclear if/when an "iPad Nano" will show up. This creates an opportunity for Android tablet competitors to control this 7" segment. Pricing is a big issue, however. Most of the "quality" 7" tablets remain too expensive (without a carrier subsidy) to drive mass adoption at this time. Most people don't want to buy another data plan as well. Amazon may change that; we'll see.
Below is data from Nielsen comparing how various connected devices are used. Smartphones are used relatively evenly throughout the day and in various locations; however tablets are used heavily during TV watching and in bed. By contrast eReaders are used most heavily in bed.
Those who would argue that tablets are a "fad" are simply mistaken. Ultimately 30% to 50% of PC usage will shift to smartphones and tablets in my opinion.